The first effective utilization of activated carbon in gold thiosulfate system: A more eco-friendly, easier method for gold recovery and material regeneration

Abstract

Employing activated carbon in the thiosulfate process has high potential applications for extracting gold. However, formidable challenges must be overcome to achieve such an application in an efficient and eco-friendly manner. Accordingly, this study aimed to develop a simple and environmentally friendly method for gold extraction. To this end, activated carbon with good gold capacity (15.9 kg/t) was synthesised for the first time by impregnating green reagent 1-methyl-5-mercapto-1,2,3,4-tetrazole (MMT), which can thermally decompose into a gas completely, and the mechanisms of adsorption and desorption process were studied. Acceptable desorption efficiency (nearly 100% in 12 h) was achieved for gold on activated carbon using environmentally safe and low-cost thiosulfate salt. More importantly, after gold desorption, the good gold adsorption performance (gold capacity of 13.8 kg/t) of activated carbon could be restored by treating it again with MMT. Additionally, green thiosulfate could be used not only as a leaching agent but as a desorbent for gold. Moreover, the results suggest that gold adsorption on MMT-AC takes place through a ligand exchange mechanism. Overall, the method reported herein exhibits good gold adsorption-desorption performance, while offering environmental friendliness and simplicity. With these achievements, this study is expected to accelerate the development of the expected potentially more environmentally friendly technology.